(first posted 7/15/2015) I’ve been infatuated with old Oliver tractors since my childhood days driving tractors, especially the 70 (and later 77). Why? In addition to wearing their late-30s Streamline Moderne styling so well, the 70 and 77 were unusual in their size-power class to have a six cylinder engine. My first time driving one brought that point home, compared to two-cylinder John Deere “poppers” that gave a deep, slow massage and the four cylinder Farmalls which just caused one’s hands to tingle after a day holding its steering wheel. Not so the silky-smooth Oliver.
A year and a half ago, I wrote up a post on one of or many visits to Hentze Farm, where we get eggs and fresh produce in season. One of the featured tractors was this Oliver 66, a bit younger and a class smaller than the 70, and with a four cylinder engine. It’s visible in the background of the top shot.
But this visit was shortly after July 4th, and a neighbor’s recently re-painted 70 was still visiting, after having been used in the nearby Harrisburg, OR, Independence Day Parade, which I hear is worth coming to see for its small town flavor and old vehicles.
This 70 is called “Standard” to differentiate from its more slender and narrow-front track “tricycle” row-crop version that was generally more popular with Iowa farmers, since it was more versatile for cultivator and other field tasks. The standard version was more typically used further out west, for plowing and pulling combines on the large wheat fields and such. There was also an orchard version which covered the rear wheels.
Here’s a row-crop 70. Oliver streamlined its line of tractors in 1937, among the first to do so, and it made for an exceptionally fine looking machine in my eyes.
Let’s lift up the the engine covers and see what’s inside. International and John Deere also redesigned the styling of their tractors about the same time, but didn’t use engine covers, for practical reasons; understandably so. But it does make the Olivers distinctive if a bit annoying.
The ohv inline six has a small 3.124″ bore and a very long 4.375″ stroke, resulting in 201.3 cubic inches (3.3 L). Like all tractor engines, its governor severely limits engine speed, to 1500 rpm in this case. Horsepower was tested independently by the rigorous Nebraska Field tests, which yielded a 31.52 hp on the belt, 30.37hp on the PTO, and 28.63 at the drawbar. The rather small updraft carburetor gives testament to the “throttled” nature of these tractor engines, which are designed to run wide-open at their rated speed all day.
Why were almost all tractor engines overhead valve, when most American cars had flatheads? Fuel efficiency was very critical to a tractor’s owner, and those Nebraska tests measured fuel usage very precisely. OHV engines burn fuel more efficiently, and thus flatheads were the exception rather than the rule. Ford naturally used flatheads on its N series tractor, but switched too ohv in 1953.
“Clean Air Filter Daily”. As if. These oil-soaked steel-mesh element filters were very effective, but messy to clean, in kerosene.
Built in Charles City, Iowa; and well built at that.
Unfortunately I didn’t get a chance to relive my memories the day I helped out at some neighbor’s farm driving their six-cylinder 70. But the distinctive sound and smooth thrumm of that Oliver six are still vivid in my memory.